Day: May 30, 2013

[Justin Beckerman] built a functioning one-man submarine. The thing is, this isn’t the first one that he’s built. Looking through the projects on his website we find almost no information about this build, but he does show off one previous model, as well as a couple of unmanned underwater rover projects.

The pressure hull of the sub is made from corrugated drainage pipe. This isn’t a bad idea as the tube is engineered to be buried in the ground and carry the load of earth on top of it. It’s designed to go down just 30 feet, which explains the lack of half-dome caps on either end; the pressure just isn’t that great at that depth. The buoy floating to his left is his tether to the surface. Fresh air is pumped from here into the sub. He’s also included safety features like a 20-minute air tank in case he gets into a bind, and a quick opening top hatch. That hatch is a hemisphere of clear acrylic which lets him view what’s around him.

You’ll learn more from the two video clips he posted. The Fox 5 news interview includes a shot of one of the messiest work benches we’ve seen. A messy bench is the sign of constant project construction, right?

Wanting to extend the capabilities of the radio frequency devices in his home [Kalle Löfgren] turned a Raspberry Pi into an RF control hub. We’ve seen some of his home automation work in the past. In his media room he built a universal remote base station which used the same RF board as in this project. The main difference is that before he went with an AVR microcontroller and this time he’s upgrade to a Raspberry Pi board.

The RPi brings a lot more to the table. Notably, the scripting (whose output is shown above) and networking features. His radio board is an nRF24L01 which he talks to via the SPI protocol. The Raspberry Pi has no problem talking to SPI devices through its GPIO header. [Kalle] just needed to do a bit of setup to configure the pin modes.

A Python script lets him sent commands using his keyboard, but this can also be automated. Combine that with the TCP server script he wrote and it opens up the a wide range of configurations to switch or talk to any device operating on the 2.4 GHz band.

Having a serial port on any Linux box is always useful, but with the tiny computers we’re carrying around in our pockets now, that isn’t always an option. Some of the more advanced phones out there break out a UART on their USB OTG port, but the designers of the Nexus 4 decided to do things differently. They chose to put the Nexus 4’s serial port on the mic and headphone input, and [Ryan] and [Josh] figured out how to access this port.

Basically, the Nexus 4 has a tiny bit of circuitry attached to the microphone input. If the Nexus detects more than 2.8 Volts on the mic, it switches over to a hardware UART, allowing everything from an Arduino to an old dumb terminal to access the port.

The guys used a USB to serial FTDI board wired up to a 3.5 mm jack with a few resistors to enable the hardware UART on their phone. With a small enclosure, they had a reasonably inexpensive way to enable a hardware serial port on a mobile device with GPS, cellular, a camera, and a whole bunch of other sensors that any portable project would love.

EDIT: An anonymous little bird told us this: “You should add a note to the Nexus 4 serial cable post that TX and RX need to be 1.8V. If you use 3.3V USB cables, you will likely eventually fry something. FTDI makes 1.8V IO cables that work – you just need to make the trigger voltage for the mic line.” Take that for what you will.

In 1979, [Nolan Bushnell] released Asteroids to the world. Now, he’s playing the game again, only this time with the help of a laser projector and a Kinect that turns anyone sitting on a stool – in this case [Nolan] himself – into everyone’s favorite vector spaceship. It’s a project for Steam Carnival, a project by [Brent Bushnell] and [Eric Gradman] that hopes to bring a modern electronic carnival to your town.

The reimagined Asteroids game was created with a laser projector to display the asteroids and ship on a floor. A Kinect tracks the user sitting and rolling on a stool while a smart phone is the triangular spaceship’s ‘fire’ button. The game is played in a 150 square foot arena, and is able to put anyone behind the cockpit of an asteroid mining triangle.

[Brent] and [Eric] hope to bring their steam carnival to LA and San Francisco next spring, but if they exceed their funding goals, they might be convinced to bring their show east of the Mississippi. We’d love to try it out by hiding behind the score like the original Asteroids and wasting several hours.

We’re pretty spoiled these days in that hobby electronics has made a lot of cool tools available on a budget. It’s hard to think of a better example than a logic analyzer, which you can get for a day or two of pay. Consumer-level devices just didn’t exist until a few years ago. [Jouko S] has this HP16500B industrial grade logic analyzer in his shop. It’s from the early 1990’s and it’s got a ton of features. Grabbing a still functional yet super-old model used to be the only way for hobbyists. But one thing you won’t find on it is the ability to connect it to your USB port to get screen captures. Younger readers might not recognize the slot at the top for magnetic media called a floppy disk which is the in-built way of recording your sessions. He set out to find an easier way to get color screen captures and ended up adding RS-232 control to the old hardware.

There is a 25-pin port on the back of the old hulk. But it is a female connector and he didn’t have the adapters on hand to make it work with his serial-to-USB converter. During development he used a breadboard and solder-tail connector to patch into the necessary signals. This was all hooked up to a Raspberry Pi which he planned to dedicate to the system. It worked, and he was able to use an interactive terminal for the rest of his sleuthing. With much trial and error he figured out the commands, and wrote some Python code for the Pi side of the equation. He can now pull color screenshots with ease thanks to the utilities available in the Python Imaging Module.